To　solve　the　problem　that　it　is　difficult　to　obtain　the　characteristics　of　particles　motion　trajectory　and　local　void　ratio　change　in　the　critical　state　of　soil　in　laboratory　tests.　Several　conventional　triaxial　numerical　models　of　granular　materials　with　different　initial　states　under　flexible　boundary　conditions　was　established　by　DEM　to　contrast　the　evaluation　characteristics　of　shear　bands　and　the　differences　in　the　overall　void　ratios　and　local　void　ratios　of　granular　materials　with　different　initial　void　ratios.The　numerical　results　show　that:The　sand　specimens　with　a　larger　initial　void　ratio　are　more　likely　to　form　shear　bands　in　the　loading　process.The　particles　in　the　shear　region　rotate　violently　with　the　loading,　and　the　flow　of　local　particles　is　turbulent.The　particles　out　of　the　shear　zone　rotation　are　not　obvious,　and　the　flow　shows　directional　characteristics.For　sand　samples　with　different　initial　void　ratios,　the　critical　state　void　ratios　on　the　shear　band　and　the　deviator　stress　ratio　are　independent　of　the　initial　void　ratio,　and　the　stable　characteristics　of　the　constitutive　tensor　invariants　of　the　critical　state　characteristics　indicate　that　the　critical　state　exists　and　is　unique.　©　2024　Editorial　Board　of　Journal　of　Basic　Science　and　Engineering.　All　rights　reserved.